1. Field of the Invention
The present general inventive concept relates to an automatic document feeder, and, more particularly, to an automatic document feeder with an improved driving structure of a pickup device, an image reading device having the same and an image forming apparatus having the same.
2. Description of the Related Art
Generally, an image reading device is a device that reads image information recorded on a document. Such an image reading device is mounted in an image forming apparatus, such as a fax machine, a digital copying machine, a multi-function printer, and the like.
An image reading device may include an automatic document feeder which automatically feeds document sheets so as to successively read the document sheets. An automatic document feeder includes a pickup device to pick up document sheets loaded on a document supply tray and feed them to a pickup device. The document sheet picked up by the pickup device is supplied to a reading unit, such as an image sensor, and image information on the document sheet is read by the reading unit.
When a user puts document sheets on a document supply tray, the pickup device is in an ascended state so as not to interfere with the document sheets. When picking up the document sheets, the pickup device is descended to the document sheets loaded on the document supply tray. In a descended state, the pickup device is in contact with a document sheet, and carries out a pickup operation.